High density mounting of semiconductor devices has been advancing in recent years, and the main focus has been on semiconductor devices such as CSP (Chip Sized Package).
In a chip-sized-package of semiconductor device, it is important to prevent cracks, which may be generated at a joint section between the semiconductor device and a mounting substrate (printed board) due to differences in the thermal expansion coefficients of the semiconductor elements and the mounting substrate.
A conventional chip size package includes a sealing resin formed on a circuit formation surface of a semiconductor element (substrate) and a surface opposite the circuit formation surface, so that warping of the wafer is prevented.
If a crack were generated at a joint section between a semiconductor device and a circuit board, connection reliability would deteriorate. Connection reliability includes certainty of mechanical and electrical contact between a CSP and a circuit board. In order to improve such connection reliability, certain materials may be filled between a CSP and a circuit board. However, manufacturing cost would be increased.